1. Field of the Invention
This invention relates to a novel heat-resistant paint containing a polymetallocarbosilane, and more specifically, to a novel heat-resistant paint comprising a polymetallocarbosilane and a filler with or without a silicone resin.
2. Description of the Prior Art
Paints comprising organopolysiloxane as a vehicle and various pigments are known as heat-resistant paints which prevent corrosion and degradation of metallic and nonmetallic substrates at high temperatures. These organopolysiloxane-type paints have better heat resistance than known paints comprising organic polymers such as polyesters and polyimides as vehicles, but in an air atmosphere at high temperatures exceeding 400.degree. C., coated films prepared from these organopolysiloxane-type paints undergo peeling from the substrates.
With an advance in industry, there has been an increasing demand for coating agents which can prevent oxidation and corrosion of metallic or nonmetallic substrates which are exposed to high temperatures above 1000.degree. C., for example aircraft component parts, and steel-making furnaces or metal smelting furnaces.
Japanese Patent Publication No. 12746/1984 discloses a process for producing a heat-resistant metallic material which comprises coating a metallic material with polycarbosilane having carbon and silicon as skeletal components and containing small amounts of metal elements, and firing the coated material at 800.degree. to 2000.degree. C. in a nonoxidizing atmosphere to convert polycarbosilane into silicon carbide. Japanese Laid-Open Patent Publication No. 84370/1980 discloses a process for obtaining a heat-resistant coated film, which comprises coating a metallic or nonmetallic material with a coating composition comprising a semiinorganic compound containing polycarbosilane and a ceramic or metal powder, and then baking the coating by heating the coated material at 400.degree. to 2,000.degree. C. in a nonoxidizing atmosphere.
Since the ratio of polycarbosilane which remains after firing at 1,000.degree. C. (in air) is about 30% by weight, high volumetric shrinkage occurs as a result of thermal decomposition of polycarbosilane during baking, and the adhesion of the baked coated film to the substrate becomes insufficient. When the baking is carried out in an oxidizing atmosphere, for example air, the coated film mostly peels from the substrate. Furthermore, the heat resistance temperature of the coated film formed is about 400.degree. C. in air. This heat resistance temperature is not much different from that of a conventional organopolysiloxane-type paint.